Problem: Adjusting rigid bodies in ART DTrack to fit with HMD eye coordinate system is time-consuming and the result might not be sufficiently accurate.

Solution: Commerical headsets are precalibrated by their makers to work correctly with the vendor-supplied tracking method. By comparing this tracking to ART tracking, the ART tracking bodies can be adjusted.

Download the calibration tool from this link.

Arrange a tracking setup where the ART tracking camera as well as the Vendor tracking system can both see and track the headset simultaneously. An example setup using Valve Tracking (using the Lighthouse base stations) is shown schematically in the image below.

Open

In case you have LPVR already installed on your system temporarily disable it.

If you have a SteamVR headset (Vive Pro, Valve Index):

First go to the SteamVR Settings menu.

Open

Make sure that the Advanced Settings slider in the lower left is set to Show. Then go to Startup / Shutdown, and to Manage Add-ons.

Open

Here change lpvr_cad or lpvr_duo to Off. A Restart SteamVR button should appear. Use it to restart SteamVR with the LPVR driver disabled.

Open

If your headset is a Varjo Headset and you have already installed the LPVR driver: go to the System tab in Varjo base, select SteamVR or Varjo Inside-Out tracking from the dropdown menu near the top

Open

Make sure that the headset tracks well. This may involve turning on the light when using inside-out tracking, adding additional Lighthouse base stations, and preventing interference of the ART system with the Lighthouses by reducing ART’s Synccard frequency and flash intensities.

The calibration tool needs full access to the ART controller, so before running it you will have to close the DTrack software.

Open the folder where you placed the downloaded openxr_art_calibration.exein the Windows explorer and double click this executable. A console window will pop up. If there are several ART controllers on your local network, the application will ask you to choose which one you want to use.

Open

Startup screen with ART controller selection

In the screenshot there are two controllers available, one is currently connected to by DTrack. Stopping DTrack this controller can be selected, and the program will continue. A menu for selection of the body to calbirate will show

Open

Selection of DTrack body to calibrate

Selecting a body will allow the program to continue. It will now wait for input from ART (labelled “Optical”) and the vendor’s tracking system (labelled “Vendor”.)

Open

Animation of a calibration run

The calibration proceeds as in the animation above. A total of ten poses will be taken, where both systems need to track the headset. The headset should be moved through a variety of orientations by turning it gently through all axes, ideally stopping every 10 degrees or so to allow the system to take data.

Open

Calibration result

Once the full set of poses has been taken, the calibration is evaluated and a quality estimate of the result is printed, indicating how well the poses between the two systems agree after calibration. Note that this is usually limited by the vendor tracking system.

Pressing the y key will update the body on the controller to use the calibration result. Once this is done, the ART body should be calibrated correctly.

The procedure described above also works for the hand controllers, but you need to use the program found behind this link, which uses the SteamVR API to access the hand controller data, and which also allows you to select between the available SteamVR devices.

Open

Open